Bone Bruises in Children and Adolescents Not Associated With Ligament Ruptures

BACKGROUND: Clinical characteristics of uncomplicated bone bruises (ie, not associated with a ligament rupture, meniscal tear, or fracture of the knee) in young athletes have scarcely been reported. PURPOSE: To identify mechanisms of injury, characterize bone bruise patterns, and identify clinical factors relating to recovery in young patients suffering uncomplicated bone bruises about the knee. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: A review of clinical records and magnetic resonance imaging (MRI) findings of patients seen at a single institution was completed. RESULTS: We identified 62 children and teenagers (mean age, 13.9 years; range, 8-18 years) who had a total of 101 bone bruises on MRI. The injuries occurred during a variety of organized and recreational sporting activities, the most common being football, basketball, and soccer. The majority (61.4%) of bone bruises occurred as a result of noncontact mechanisms. Patients reported a mean pain scale score of 6.3 of 10 (range, 2-10) on presentation. Frequent clinical findings included non–joint-line tenderness (64.5%), limited range of motion (58.1%), joint-line tenderness (54.8%), and positive meniscal signs (50.0%). The majority of bone bruises (61.4%) were located medially, and the most common bone bruise type was subcortical (58.4%), followed by medullary/reticular (35.6%) and articular impaction (5.9%). The only factor related to time to recovery was mechanism of injury; patients reporting a noncontact mechanism required significantly more time to recover than those reporting a contact mechanism (mean, 99.7 ± 74.8 vs 65.7 ± 38.8 days, respectively; F = 3.753, P = .049). CONCLUSION: In this case series of 62 pediatric patients with non–anterior cruciate ligament (ACL) bone bruises, the majority occurred in the medial compartment, suggesting that these bone bruises result from a mechanism distinct from the pivot-shift mechanism, classically thought to cause ACL injuries.